Hi,
I have been designing passive optical components (AWGs, splitters, etc.) for many years. I know also other photonics software tools (Apollo Photonics, R-Soft, etc.). Regarding optiBPM (WDM-Phasar) this tool is slower than the other tools but it offers the simulation results that match the best with the measurements and therefore it is my favourite. See: D.Seyringer, F.Uherek, J.Chovan and A.Kuzma: Design, Simulation and Evaluation of AWG Based Demultiplexers, 2012 IEEE International Conference on Advanced Semiconductor Devices & Microsystems (ASDAM), 11 to 15 November 2012, Smolenice (Slovakia), Published in IEEE Electron Devices (2013).DOI: 10.1109/ASDAM.2012.6418537